Waveform generator for microdeposition control system

ABSTRACT

A microdeposition system ( 20 ) and method includes a head with a plurality of nozzles ( 230 ). A controller ( 22 ) generates nozzle firing commands that selectively fire the nozzles to create a desired feature pattern. Configuration memory stores voltage waveform parameters that define a voltage waveform ( 280 ) for each of the nozzles. A digital to analog converter (DAC) sequencer communicates with the configuration memory and the controller and outputs a first voltage waveform for a first nozzle when a nozzle firing command for the first nozzle is received from the controller ( 22 ). A resistive ladder DAC receives the voltage waveforms from the DAC sequencer. An operational amplifier (opamp) communicates with the resistive ladder DAC and amplifies the voltage waveforms. The nozzles fire droplets when the voltage waveforms received from the opamp exceed a firing threshold of the nozzle ( 230 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/295,118, entitled “Formation of MicrostructuresUsing Piezo Deposition of Liquid Onto Substrate,” filed Jun. 1, 2001,and U.S. Provisional Application Ser. No. 60/295,100, entitled FormationOf Printed Circuit Board Structures Using Piezo Deposition Of LiquidOnto Substrate, filed Jun. 1, 2001, each of which is incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates to microdeposition systems, and moreparticularly to waveform generators for microdeposition systems forfabricating printed circuit boards, polymer light emitting diode (PLED)displays, and other devices requiring microdeposition of fluid material.

BACKGROUND OF THE INVENTION

Manufacturers have developed various techniques for fabricatingmicrostructures that have small feature sizes on substrates. Typicallythe microstructures form one of more layers of an electronic circuit.Examples of these structures include light-emitting diode (LED) displaydevices, polymer light-emitting diode (PLED) display devices, liquidcrystal display (LCD) devices, printed circuit boards and the like. Mostof these manufacturing techniques are relatively expensive to implementand require high production quantities to amortize the cost of thefabrication equipment.

One technique for forming microstructures oh a substrate includes screenprinting. During screen printing, a fine mesh screen is positioned onthe substrate. Fluid material is deposited through the screen and ontothe substrate in a pattern defined by the screen. Screen printingrequires contact between the screen and the substrate. Contact alsooccurs between the screen and the fluid material, which contaminatesboth the substrate and the fluid material.

While screen printing is suitable for forming some microstructures, manymanufacturing processes must be contamination-free to produceoperational devices. Therefore, screen printing is not a viable optionfor the manufacture of certain microstructures. For example, polymerlight-emitting diode (PLED) display devices require a contamination-freemanufacturing process.

Certain polymeric substances can be used in diodes to generate visiblelight of different wavelengths. Using these polymers, display deviceshaving pixels with sub-components of red, green, and blue can becreated. PLED fluid materials enable full-spectrum color displays andrequire very little power to emit a substantial amount of light. It isexpected that PLED displays will be used in the future for variousapplications, including televisions, computer monitors, PDAs, otherhandheld computing devices, cellular phones, and the like. It is alsoexpected that PLED technology will be used for manufacturinglight-emitting panels that provide ambient lighting for office, storage,and living spaces. One obstacle to the widespread use of PLED displaydevices is the difficulty encountered to manufacture PLED displaydevices.

Photolithography is another manufacturing technique that is used tomanufacture microstructures on substrates. Photolithography is also notcompatible with PLED display devices Manufacturing processes usingphotolithography generally involve the deposition of a photoresistmaterial onto a substrate. The photoresist material is cured by exposureto light. A patterned mask is used to selectively apply light to thephoto resist material. Photoresist that is exposed to the light is curedand unexposed portions are not cured. The uncured portions are removedfrom the substrate.

An underlying surface of the substrate is exposed through the removedphotoresist layer. The cured portions of the photoresist layer remain onthe substrate. Another material is then deposited onto the substratethrough the opened pattern on the photoresist layer, followed by theremoval of the cured portion of the photoresist layer.

Photolithography has been used successfully to manufacture manymicrostructures such as traces on circuit boards. However,photolithography contaminates the substrate and the material formed onthe substrate. Photolithography is not compatible with the manufactureof PLED displays because the photoresist contaminates the PLED polymers.In addition, photolithography involves multiple steps for applying andprocessing the photoresist material. The cost of the photolithographyprocess can be prohibitive when relatively small quantities are to befabricated.

Spin coating has also been used to form microstructures. Spin coatinginvolves rotating a substrate while depositing fluid material at thecenter of the substrate. The rotational motion of the substrate causesthe fluid material to spread evenly across the surface of the substrate.Spin coating is also an expensive process because a majority of thefluid material does not remain on the substrate. In addition, the sizeof the substrate is limited by the spin coating process to less thanapproximately 12″, which makes spin coating unsuitable for largerdevices such as PLED televisions.

SUMMARY OF THE INVENTION

A microdeposition system and method includes a head with a plurality ofnozzles. A controller generates nozzle firing commands that selectivelyfire the nozzles to create a desired feature pattern. Configurationmemory stores voltage waveform parameters that define a voltage waveformfor each of the nozzles.

In other features, a digital to analog converter (DAC) sequencercommunicates with the configuration memory and the controller andoutputs a first voltage waveform for a first nozzle when a nozzle firingcommand for the first nozzle is received from the controller. Aresistive ladder DAC receives the voltage waveforms from the DACsequencer. An operational amplifier (opamp) communicates with theresistive ladder DAC and amplifies the voltage waveforms. The nozzlesfire droplets when the voltage waveforms received from the opamp exceeda firing threshold of the nozzle.

In other features, the nozzles include a common line and a nib line. Thecommon line is connected to one of earth ground and a floating positivevoltage relative to a system power ground. The opamp drives the nib lineto a negative voltage that exceeds the firing threshold voltage to firethe nozzle.

In still other features, a first voltage waveform that is associatedwith a first nozzle includes at least one of a positive conditioningpulse and a negative conditioning pulse that does not exceed the firingthreshold. The positive conditioning pulse or the negative conditioningpulse precedes or follows a firing pulse that exceeds the firingthreshold.

In still other features, a configuration latch receives a set of voltagewaveform parameters from the controller and loads the set of voltagewaveform parameters in the configuration memory. A pixel latchcommunicates with the DAC sequencer and receives nozzle firing commandsfrom the controller. The configuration memory stores a plurality of setsof voltage waveform parameters for each of the nozzles. A configurationset selector selects one of the sets of voltage waveform parametersbased on operating conditions of the nozzle.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of a microdeposition systemaccording to the present invention;

FIG. 2 is a functional block diagram of a controller for themicrodeposition system of FIG. 1;

FIG. 3 illustrates marks on a substrate that are used to position themicrodeposition head;

FIG. 4 illustrates alignment of the head using optical characterrecognition and the marks;

FIG. 5 illustrates a nozzle of an exemplary microdeposition head;

FIG. 6 illustrates shearing of a piezo transducer during firing of theexemplary microdeposition head of FIG. 5;

FIGS. 7 and 8 are exemplary cross-sections of monochrome and colorpolymer light emitting diodes (PLEDs);

FIG. 9 illustrates controlled drying of a fluid material such as (PPV)polymer that has been deposited on a substrate;

FIG. 10 illustrates a manufacturing process for a printed circuit boardaccording to the prior art;

FIG. 11 illustrates the use of the microdeposition system for depositinga resist fluid material onto a copper clad dielectric substrate for aprinted circuit board;

FIG. 12 illustrates the use of the microdeposition system for depositinga conductive fluid material onto a dielectric substrate to create tracesfor a printed circuit board;

FIGS. 13A and 13B illustrate the microdeposition of resistive fluidmaterials to create resistors on printed circuit boards;

FIG. 14 illustrates the microdeposition of a capacitor;

FIG. 15 illustrates a printed circuit board replacement according to thepresent invention using a laminated insulator over microdepositedtraces;

FIG. 16 illustrates a multilayer printed circuit board includinginternal microdeposited resistors, capacitors and/or traces;

FIG. 17 illustrates a light panel including microdeposited pixels on apixel plate and/or microdeposited fuses on an optional fuse plate;

FIG. 18 illustrates a waveform generator that is capable of generatingdifferent firing waveforms for each nozzle;

FIG. 19 illustrates rise slope, duration, timing and fall slope of anexemplary nozzle firing waveform;

FIG. 20 illustrates modification of rise slope, duration, timing and/orfall slope for several exemplary nozzle firing waveforms using thewaveform generator of FIG. 18;

FIG. 21 is a functional block diagram of a nozzle drive circuitaccording to the prior art;

FIG. 22 is a functional block diagram of a nozzle drive circuitaccording to the present invention;

FIG. 23 is a functional block diagram of an exemplary waveformgenerator;

FIG. 24 illustrates the configuration memory including one or moreconfiguration sets;

FIG. 25 illustrates waveform timing adjustment using a pitch timingadjuster that adjusts waveform timing of the configuration sets;

FIG. 26 illustrates a waveform associated with an exemplaryconfiguration set;

FIG. 27 illustrates an exemplary configuration set data structure;

FIG. 28A-28D illustrate exemplary waveforms associated with multipleconfigurations sets;

FIGS. 29A-29C illustrates drop formation analysis;

FIG. 30 illustrates drop alignment;

FIGS. 31A and 31B illustrates pitch adjustment of the microdepositionhead;

FIG. 32 illustrates an exemplary use of over-clocking to adjust forpitch changes of the microdeposition head;

FIG. 33 illustrates an example of over-clocking to allow rapid nozzlefiring and overlapping of the applied fluid material;

FIG. 34 illustrates overlapping droplets;

FIGS. 35A and 35B illustrate nozzle adjustments to provide uniformdroplets;

FIG. 36 illustrates a diagonal feature that is created withoutover-clocking;

FIG. 37 illustrates a diagonal feature that is created withover-clocking;

FIG. 38 illustrates multiple microdeposition heads that are attachedtogether to provide reduced pitch; and

FIG. 39 illustrates multiple adjustable microdeposition heads that areattached together to provide adjustable pitch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For purposes of clarity, the same referencenumbers will be used in the drawings to identify similar elements.

Referring now to FIG. 1, a microdeposition system 20 is illustrated andincludes a controller 22, a head assembly 24, and a substrate assembly26. A rotational position or pitch of the head assembly 24 is adjustedusing a rotary position motor 30 and a rotary position sensor 32.Likewise, a height of the head assembly 24 relative to the substrateassembly 26 may be adjusted using a height adjustment motor 34 and aheight sensor 36. A lateral position of the head assembly 24 is adjustedusing a lateral position motor 40 and a lateral position sensor 42.

A microdeposition head 50 with a plurality of nozzles is mounted on thehead assembly 24. Additional details are found in contemporaneouslyfiled PCT Patent Application No. ______, filed May 31, 2002, entitledMicrodeposition Apparatus; PCT Patent Application No. ______, filed May31, 2002, entitled Temperature Controlled Vacuum Chuck; PCT PatentApplication No. ______, filed May 31, 2002, entitled IndustrialMicrodeposition System For Polymer Light Emitting Diode Displays,Printed Circuit Boards And The Like; PCT Patent Application No. ______,filed May 31, 2002, entitled Interchangeable Microdeposition HeadApparatus And Method; PCT Patent Application No. ______, filed May 31,2002, entitled Over-Clocking In A Microdeposition Control System ToImprove Resolution; PCT Patent Application No. ______, filed May 31,2002, entitled Formation Of Printed Circuit Board Structures Using PiezoMicrodeposition; and PCT Patent Application No. ______, filed May 31,2002, entitled Apparatus For Microdeposition Of Multiple FluidMaterials; each of which is incorporated herein by reference. A firstcamera 52 is mounted on the head assembly 24. The first camera 52 isused to position the head assembly 24 relative to a substrate 53 that islocated on the substrate assembly 26. More particularly, the firstcamera 52 is used to align the microdeposition head 50 using one or morenozzles of the head 50 as a reference. In addition, the first camera 52is used to perform drop analysis on the substrate, as will be describedmore fully below.

A laser 60 can be used for laser ablation of applied fluid material toreduce minimum feature sizes and/or for creating vias. While the laser60 is mounted on the head assembly 24 in FIG. 1, the laser 60 can bemounted on a laser assembly that moves independently from the headassembly 24. A fluid supply 62 is connected by one or more conduits 64to the microdeposition head 50. The fluid supply 62 provides one or moredifferent types of fluid materials, such as polymer PPV for red, greenand blue pixels, solvent, resistive fluid materials, conductive fluidmaterials, resist fluid materials, and/or insulating fluid materials.The fluid supply 62 is preferably capable of changing the fluid materialthat is supplied by using a solvent flush before switching a new fluidmaterial.

A lateral position motor 64 and a lateral position sensor 66 are used toposition the substrate assembly 26 with respect to the head assembly 24.In a preferred embodiment, the lateral position motor 40 moves along afirst axis. The lateral position motor 64 moves along a second axis thatis perpendicular to the first axis. As can be appreciated by skilledartisans, the position motors 30, 34, 40 and 64 are associated witheither the head assembly 24 or the substrate assembly 26. In otherwords, the degrees of relative movement and rotation may be provided bymoving or rotating the substrate assembly 26 and/or the head assembly 24and any combination thereof.

A blotting station 70 and a blotting media motor 72 are preferablylocated adjacent to the substrate assembly 26. To prevent clogging ofnozzles of the microdeposition head 50, the microdeposition head 50 iscleaned periodically during use. The microdeposition head 50 is movedinto position over the blotting station 70 and a nozzle plate (notshown) of the microdeposition head is wiped on the blotting station 70.The blotting station 70 includes a roll of blotting material. A blottingmotor 72 advances the roll of blotting material to provide a cleansurface for blotting of the nozzle plate of the microdeposition head 50.

A capping station 80 is also located adjacent to the head assembly 24.The microdeposition head 50 is parked in the capping station 80 when themicrodeposition system 20 is not in use. The capping station 80 includesa cup containing wet fluid material and/or solvent. The capping station80 is used to prevent the fluid material that is delivered by themicrodeposition head 50 from clogging the nozzles of the microdepositionhead 50. A second camera 84 is used for droplet analysis and is locatedadjacent to the capping station 80. Preferably, the first and secondcameras 52 and 84 and the controller 22 provide digital opticalrecognition, as will be described more fully below. A strobe 85 may beprovided to capture the droplets.

The substrate assembly 26 includes a chuck 86, which engages andpositions the substrate 53. The substrate assembly 26 preferablyincludes a curing device such as a temperature controller 90 and/or anultraviolet (UV) source 92. The temperature controller 90 controls thetemperature of the chuck 86. A temperature of approximately 50° C. istypically suitable to reduce drying times for substrates havingthicknesses between 0.3 and 1.2 mm. The chuck 86 preferably includes avacuum circuit that positions and engages the substrate 53. Alternately,the chuck 86 may include other types of devices that position and engagethe substrate 53 during microdeposition. For example, fluid surfacetension, magnetism, physical engagement of the substrate or any otherapproach may be used to engage the substrate 53 during microdeposition.Additional details concerning the chuck are found in “TemperatureControlled Vacuum Chuck”, Ser. No. ______, filed _, which is herebyincorporated by reference.

Skilled artisans will appreciate that manual adjustment devices such asa hand adjustment (for example, a knob that turns a worm gear or anyother mechanical adjustment) can be used to replace one or more of themotors 30, 34, 40, and 64 to reduce cost. Visual devices such as a scalecan be used to replace one or more of the sensors 32, 36, 42, and 66 toreduce cost. In addition, the function of the motors 30, 34 and/or 40may be combined in a multi-axis motor if desired. In a preferredembodiment, one or more of the positioning devices are implemented usingan air bearing and a linear motor. Still other variations will beapparent to skilled artisans. The functionality that is provided by themotors and sensors is similar to a computer numerical controlled (CNC)milling machine. Preferably, the motors provide adjustment in three ormore axes. Additional ranges of motion can be provided forthree-dimensional (3D) microdeposition or microdeposition of complexcurved shapes.

The microdeposition head 50 is preferably positioned over the substrateat a distance of between approximately 0.5 mm and 2.0 mm. In a highlypreferred embodiment, the microdeposition head is positioned a distancethat is at least 5 times the size of the droplet of the fluid material,although other heights may be used. When smaller pitch sizes arerequired, the microdeposition head 50 is rotated to reduce the pitch.When larger pitches are required, the microdeposition head 50 is rotatedand some of the nozzles are not used, for example every other nozzle isnot used.

Referring now to FIG. 2, the controller 22 is illustrated in furtherdetail. The controller 22 includes one or more processors 100, memory102 (such as random access memory (RAM), read-only memory (ROM), flashmemory, and/or any other suitable electronic storage medium), and aninput/output interface 104. As can be appreciated, while a singlecontroller 22 is shown, multiple controllers may be used. A dropanalysis module 110 performs drop analysis using the first camera 52and/or second camera 84, as will be described more fully below.

An alignment module 112 preferably aligns the substrate and the head 50using optical character recognition (before depositing the fluidmaterial) using the first camera 52 and/or the second camera 84. Anozzle position and firing module 114 adjusts the position of the headassembly 24 with respect to the substrate 53 and generates nozzle firingwaveforms to create features on the substrate. A waveform generatingmodule 116 operates in conjunction with the nozzle position and firingmodule 114 and adjusts the timing, rise slope, fall slope, and/oramplitude of nozzle firing waveforms, as will be described more fullybelow. The waveform generating module 116 also optionally adjusts nozzlefiring timing for changes in the pitch of the head.

Referring now to FIGS. 3 and 4, the substrate 53 preferably includes aplurality of marks 117-1, 117-2, 117-3, . . . 117-n that are used by thefirst camera 52 and/or the second camera 84 to align the substrate 53and the head 50 before depositing the fluid material(s). Rough initialpositioning may be performed manually if desired. Alternately, thealignment module 112 may use optical character recognition to performrough and/or fine alignment using the marks 117.

Referring now to FIG. 5, an exemplary microdeposition head 50 is shownin further detail. The present invention will be described inconjunction with a shear mode piezo transducer (PZT) microdepositionhead. Skilled artisans will appreciate that other types ofmicrodeposition heads are contemplated such as thermal or bubblemicrodeposition heads, continuous drop microdeposition heads, PZTvalves, and microelectromechanical valves. The microdeposition head 50includes a PZT 130 that is located on a diaphragm 134. While only onenozzle is shown, skilled artisans will appreciate that themicrodeposition head 50 includes a plurality of nozzles.

The fluid supply 62 provides one or more fluid materials via one or moreconduits 138 to a fluid channel 139 that is formed between the diaphragm134 and rigid walls 140. A nozzle plate 142 includes a nozzle opening144 formed therein. Electrical lead(s) (not shown) connect the PZT 130to the controller 22. The controller 22 transmits nozzle firingwaveforms that produce an acoustic pulse 148. The acoustic pulse travelsthrough the fluid material in the fluid channel 139 and fires a droplet150. The shape, volume and timing of the droplet is controlled by thenozzle firing waveform.

The microdeposition head 50 dispenses precise droplets 150 of fluid ontothe substrate 53. More particularly, the microdeposition head assembly24 is precisely positioned relative to the substrate 53 using thecontroller 22 of the microdeposition system 20. As a result, themicrodeposition head 50 is able to place droplets in precise locationson the substrate 53.

When the nozzle firing waveforms are triggered by the controller 22,shear mode actuation causes the droplet 150 to be dispensed. Typically,the microdeposition head 50 will include between 64 and 256 nozzles,although additional or fewer nozzles may be utilized. Each nozzle 144 ofthe microdeposition head 50 is capable of dispensing between 5000-20,000drops per second, although higher or lower drop dispensing rates may beprovided. Typically, each droplet contains between 10 and 80 picolitersof fluid material depending upon the type of microdeposition device thatis used, although increased or decreased droplet volume may be provided.Referring now to FIG. 6, the shear mode PZT 130 is illustrated further.When an electric field is applied, the PZT 130 responds by shearing,which creates the acoustic wave 148.

Referring now to FIGS. 7 and 8, exemplary devices that can be fabricatedusing the microdeposition system 20 are shown. In FIG. 7, a monochromePLED 160 is shown and includes a substrate 164, which may include one ormore glass layers 166 and/or silicon layers 168. Resists 170 arefabricated on the substrate 164 using any suitable fabrication techniquesuch as photolithography, etching, etc. Wells 172 are formed between theresists 170. The microdeposition head 50 deposits one or more fluidmaterials into the wells 172. For example, a first layer 176 is indiumtin oxide (ITO). A second layer 180 is polyaniline (PANI). A third layer182 is PPV polymer.

Referring now to FIG. 8, a color PLED 190 is shown and includes asubstrate 194 with one or more glass layers 196 and/or silicon layer(s)198. Resists 200 are fabricated on the substrate 194 and form wells 202.The microdeposition system 20 is used to form multiple layers in thewells 202. For example, a first layer 204 includes ITO. A second layer206 includes PPV polymer. A third layer 208 includes ITO. A fourth layer210 provides a cap layer.

Referring now to FIG. 9, some fluid materials that will be dispensed bythe microdeposition head 50 shrink substantially as the fluid materialdries. To that end, curing devices are preferably provided with thesubstrate assembly 26 to control curing and shrinkage. The temperaturecontroller 90 and/or ultraviolet (UV) source 92 are provided tofacilitate proper curing of the fluid material that is deposited in thewells. For example, the temperature controller 90 heats the chuck 86,which warms the substrate 53 through contact. Alternately, the UV source92 generates ultraviolet light that is directed at the fluid materialthat is deposited on the substrate 53 to facilitate curing.Additionally, airflow in a vicinity surrounding the substrate assemblymay be controlled (prevented) using an enclosure, a fan, or othersuitable airflow equipment. Equipment that is typically used in a cleanroom may be employed.

When the fluid material is initially applied, it may form a bubble asshown at 210. If left to dry at ambient conditions, the dry fluidmaterial may appear as shown at 211, 212 or 213. If processed properly,the dry fluid material has the appearance shown at 214. The specificcombination of airflow, UV light and/or temperature that provide theuniform surface 214 are dependant upon the fluid material that isselected.

Referring now to FIG. 10, manufacturing of a conventional printedcircuit board (PCB) is illustrated. A photoresist is applied to a copperclad dielectric substrate 215. A light source 216 and a mask 217 areused to expose select portions of the photoresist. The exposure of theselect portions causes the photoresist to harden. The unexposed portionsof the photoresist are etched to produce a PCB 218 with traces.

Referring now to FIG. 11, using the microdeposition system 20 accordingto the present invention, a resist replacement 219 such as an acrylicpolymer is microdeposited onto the copper clad dielectric material 215before etching. As a result, the mask and exposure process iseliminated.

Alternately, the microdeposition system 20 is used to deposit a metallicink or another metallic conducting fluid 220 containing a metal powderto create traces 221 on a dielectric substrate 222. The copper foil orcladding need not be provided on the dielectric substrate 222 and themask and etching steps need not be performed. The metallic ink ormetallic conducting fluid 220 creates conductor paths or traces on thedielectric material 222. Suitable metallic fluids include solutions ofcopper, silver, and indium oxide. Depending upon the fluid material thatis used, a flash baking process is preferably used to cure and unify thetraces 221.

In addition, fluids having resistive properties such as resistive inksare used to create resistors and capacitors. For example, in FIGS. 13Aand 13B, a plurality of resistive fluid material such as resistive inksare used to deposit resistive droplets 223-1 and 223-1. The droplets arecombined to create resistors 223-3, 223-4, and 223-5 having variousresistor values. For example, if the first droplets 224-1 provides a 10k Ohm (Ω) resistance and the second droplet 224-2 provide a 1 kΩresistance, the resistor 223-5 is a 5 kΩ resistor, the resistor 223-4 isa 6 kΩ resistor and the resistor 223-3 is a 7 kΩ resistor. As can beappreciated by skilled artisans, other resistor values for the dropletsand other droplet combinations can be created. The microdepositionsystem may also be used to deposit legends, solder mask, solder pasteand other fluid materials that are used in printed circuit boardmanufacturing. Laser trimming of the deposited droplets is preferablyemployed to improve accuracy. In FIG. 14, capacitors 224 are created bymicrodepositioning using conductive traces 224-1 and 224-2 and spacedplates 224-3 and 224-4.

In an alternate embodiment in FIG. 15, traces 226 are deposited on ablank substrate or a back of a display (both identified by 227) usingthe microdeposition system 20. An insulating layer 228 is laminated overthe traces using a fluid material with insulating properties such as anacrylic polymer. Additional traces and insulating layers can be added ifneeded. If polyimide film such as Kaptone is used as the laminatedinsulating layer 228, the laser 60 is used to create vias between traceson different layers. Alternately, the insulating layer is microdepositeddirectly onto the substrate over the traces 226 or over the entiresurface.

Referring now to FIG. 16, the resistors 223 and the capacitors 224 arefabricated using microdeposition between layers of a multilayer PCB thatmay include discrete circuit components. The fabrication of theresistors between the layers allows valuable outer surface area to beused for the discrete circuit components. Additional details are foundin “Method for Manufacturing Printed Circuit Boards”, Ser. No. ______,filed _, which is hereby incorporated by reference.

Referring now to FIG. 17, the microdeposition system of the presentinvention may also be used to fabricate a pixel plate 229 of a lightpanel 230. The light panels also include a pixel diffusion plate 231 andan optional fuse plate 232. The optional fuse plate may include fusesand traces that are microdeposited.

Referring now to FIGS. 18 and 19, nozzle firing waveforms for each ofthe nozzles 234-1, 234-2, 234-3, . . . , and 234-n are individuallycontrolled by the controller 22. By controlling the nozzle firingwaveforms individually, the uniformity of droplets 150 is significantlyimproved. In other words, if the droplets 150 from a particular nozzlehave a non-uniform or undesirable shape, the nozzle firing waveform forthe corresponding nozzle is adjusted to provide a droplet 150 with auniform or desired shape. The waveform generating module 116, the dropanalysis module 110 and/or the position and firing modules 114 collectdata using the first and/or second cameras 52 and 84 and opticalrecognition. Adjustments may be made automatically using software andfeedback from droplet analysis.

More particularly, the waveform generating module 116 communicates withwaveform generators 236-1, 236-2, 236-3, . . . , and 236-n toindividually adjust timing, duration, amplitude, rise slope and/or fallslopes of the nozzle firing waveforms for each of the nozzles 234. InFIG. 19, an exemplary nozzle firing waveform 240-1 is shown. Theexemplary nozzle firing waveform 240-1 has a duration timing t_(D)241-1, a rise slope 242-1, a fall slope 244-1 and amplitude 246-1.

Referring now to FIG. 20, the exemplary nozzle firing waveform 240-1 maybe adjusted in a plurality of different ways. For example, the duration241-2 is increased as shown at 240-2. Likewise, the duration can bedecreased (not shown). The rise slope 243-3 and fall slope 244-3 of thenozzle firing waveform 240-3 is decreased and the duration 241-3 of thenozzle firing waveform 240-3 is increased. Alternately, the timing ofthe nozzle firing waveform can be adjusted as shown at 240-4. Stillother variations will be apparent to skilled artisans.

Referring now to FIG. 21, a conventional nozzle drive circuit 250according to the prior art is illustrated and includes a fixed voltagesource 251, a nozzle 252, and a switch 253. The switch 253 applies thefixed voltage across the nozzle 252 when the switch 253 is closed tofire the nozzle 252. Ground 254 is connected as shown. In theconventional nozzle driver circuit 250, the head 50 is configured forcurrent flow into a common bar and out of a nib line when firing asshown by the arrow.

Referring now to FIG. 22, a nozzle drive circuit 255 according to thepresent invention is shown and includes a waveform generator 256 that isconnected to a nozzle 257 and ground 258 as shown. The waveformgenerator 256 produces an adjustable voltage waveform. To maintain thesame current polarity for firing, the nozzle drive circuit 255 holds thecommon line at ground and drives the nib line negative. The ground is atearth ground or at a floating positive voltage relative to the systempower ground.

Referring now to FIG. 23, the waveform generating module and thewaveform generators are shown in further detail. The controller 22 isconnected via a bus 260 to a FIFO register 261. The FIFO register 261 isconnected to a datapath sequencer 262 and shift registers 263. Thedatapath sequencer 262 is coupled to a configuration controller 264,which is coupled to a configuration latch 265, a pixel latch 266, andone or more digital to analog converter (DAC) sequencers 267-1, 267-2, .. . , and 267-n (that are collectively referred to using referencenumber 267). The configuration latch 265 and the pixel latch 266 arecoupled to shift registers 268. The pixel latch 266 is coupled to theDAC sequencers 267. The configuration latch 265 is connected to one ormore configuration memory circuits 269-1, 269-2, . . . , and 269-n,which is random access memory (RAM) or any other suitable electronicstorage.

Outputs of the DAC sequencers 267-1, 267-2, . . . , and 267-n arecoupled to weighted resistive ladder DAC circuits (RDAC) 270-1, 270-2, .. . , and 270-n (which are collectively identified using referencenumber 270). Outputs of the RDAC 270-1, 270-2, . . . , and 270-n arecoupled to high-voltage operational amplifiers (OpAmp) 271-1, 271-2, . .. , and 271-n, which generate the output voltage that drives the nozzles230. If the configuration memory 269 includes more than oneconfiguration set, selectors 272-1, 272-2, . . . , 272-n are used toselect one of the configuration sets as will be described more fullybelow. While a selector 272 is shown for each configuration memory 269,a single selector for all of the configuration memories is used. Thecommon selector switches all of the configuration sets individually orjointly.

In a preferred embodiment, the opamps 271 operate from +150V and −15Vvoltage supplies (not shown) and have a signal range from 0V to +135V,although other voltage ranges can be used. Head common is connected toeither voltage supply rail or to a midpoint between the voltage supplyrails. The voltage waveforms that are output by the opamps 271 aredefined by one of more configuration sets including voltage and durationpairs. In a preferred embodiment, the voltage and duration pairs aredefined by eight voltage and duration values designated v0,t0 to v7,t7that are stored in the corresponding configuration memory 267.

Referring now to FIG. 24, the configuration memory 269 can include oneor more configuration sets 276-1, 276-2, . . . , and 276-n. As will bedescribed more fully below, a first configuration set 276-1 is selectedfor a first operating condition, a second configuration set 276-2 isselected for a second operating condition, and an nth configuration set276-n is selected for an nth operating condition. The selector 272 isused to select between the configuration sets 276. One possible use ofmultiple configuration sets will be described further in conjunctionwith FIGS. 9G-9J below. The configuration latch 265 is used to transferconfiguration sets to the configuration memory 269. The pixel latch isused to transfer pixel firing data to the DAC sequences 267.

Referring now to FIG. 25, one method for adjusting for changes in thepitch of the head 50 is illustrated. A pitch timing adjuster 277receives a head pitch signal from the controller 22. The pitch timingadjuster 277 uses the head pitch angle and the nozzle spacing to adjustthe nozzle firing parameters for each nozzle. Timing offsets aregenerated and used to adjust the voltage and duration pairs.

Referring now to FIG. 26, a voltage waveform corresponding to anexemplary configuration set 276 is illustrated. The first voltage andduration pair v0, t0 in the exemplary configuration set 276 is used forstoring up-slope and down-slope data. The last voltage and duration pairv7, t7 in the sequence preferably has t=0, which stops the waveformgeneration sequence. The output voltage preferably stays at a level thatis set by a prior voltage and duration pair. For example, if t7=0 theoutput voltage remains at v6. When a new waveform segment such as v2,t2is started, the voltage ramps from v1 to v2 at the down or up-slope asspecified in v0,t0. The amount of time that is required to ramp thevoltage is part of the specified duration t2. If the ramp takes lessthan the duration, the voltage waveform stays at the target voltage fora period that is equal to the duration minus the ramp time. If the ramptakes longer than the duration, the target voltage will not be achieved.

For example in FIG. 26, the voltage portion of the voltage and durationpair v1, t1 does not require a ramp because the voltage is equal to thevoltage portion of the voltage and duration pair v4, t4. The voltage v2is less than v1. Therefore, the voltage waveform ramps downwardly at therate specified by v0, t0 until the voltage portion is equal to v2. Sincet2>the ramp time, the voltage waveform remains at v2 for the remainderof t2.

The voltage v3 is greater than v2. Therefore, the voltage waveform rampsupwardly towards v3. Since t3> the ramp time, the voltage waveformremains at v3 for the remainder of t3. The voltage v4 is less than v3.Therefore, the voltage waveform ramps downwardly from v3 to v4. Theremaining voltage and duration pairs (t5, t6, and t7) are set equal to 0to identify the end of the sequence. Referring now to FIG. 27, anexemplary data structure for a configuration set 276 is illustrated.

Referring now to FIGS. 28A-28D, exemplary voltage waveforms that aregenerated by configuration sets 276 are illustrated. A first voltagewaveform 280 is used if the nozzle has been fired recently, in otherwords within a predetermined period. The predetermined period isselected depending upon the properties of the fluid material and thenozzle. A typical value for the predetermined period is 5 milliseconds.

A firing threshold is illustrated at 281. The voltage waveform 280exceeds the firing threshold 281 at 282 to eject the fluid material fromthe nozzle. Second or third voltage waveforms 283 or 284 is used whenthe nozzle has not fired within a predetermined period to provide animproved droplet profile. The voltage waveform 283 includes positivepulses 285 that do not exceed the firing threshold 281. The positivepulses 285 precede and/or follow a portion of the waveform that exceedsthe firing threshold 281. Likewise, the voltage waveform 284 includesnegative pulses 286 that do not exceed the firing threshold 281. Thenegative pulses 286 precede and/or follow a portion of the waveform thatexceeds the firing threshold 281. A fourth voltage waveform 287 includespositive pulses 288-1 and/or negative pulses 288-2 that do not exceedthe firing threshold 281. The pulses 288 are used to keep the fluidmaterial dispensed by the nozzle in a liquid state and/or a statesuitable for deposition. As can be appreciated, the portion of thevoltage waveform that exceeds the firing threshold may be preceded byone or more positive and/or negative pulses of the same and/or differentamplitudes.

The fourth voltage waveform 287 may be used when the nozzle has not beenfired recently. The opamps 271 are transitioned from the voltagewaveform 287 to the voltage waveforms 280, 282 or 284 when transitioningfrom non-firing to firing models. Likewise, the opamp transitions fromthe voltage waveforms 282 or 284 to the voltage waveform 280 when thenozzle is transitioning from reduced activity to increased activity.

The selector 272 is used to select between the configuration sets. Forexample, the selector 272 receives firing commands that are output bythe sequencer 267. The selector 272 includes a timer that is reset whenthe firing commands are received. If the timer is less than a firstpredetermined period, the selector 272 selects a first configuration set276-1. If the timer exceeds the first predetermined period, the selector272 selects a different configuration set, e.g. 276-2. The selector 272alternately receives sensor inputs from temperature sensors that sense atemperature of the fluid material and selects one of the configurationsets 276 based on the temperature. Still other methods for selecting theconfiguration set 276 will be apparent to skilled artisans.

Referring now to FIGS. 5 and 29A-29C, the first and/or second cameras 52and 84 are used to capture droplets 150 in flight. The drop analysismodule 110 employs optical recognition to analyze the droplets 150 andto adjust the amplitude, timing, slope, shape, etc. of the firingvoltage waveforms. The cameras are preferably digital cameras withstrobes. For example in FIG. 29A, a first droplet 300 is shown withoutcorrection of the nozzle firing waveform. With correction of the nozzlefiring waveform, a second droplet 304 from the same nozzle has thedesired shape and size. In FIG. 29B, the first droplet 306 from a nozzlehas a first voltage amplitude. A second droplet 308 from the same nozzlehas a second voltage amplitude that is lower than the first voltageamplitude. As a result, the size of the second drop 308 is smaller thanthe size of the first drop 306. In FIG. 29C, the drop analysis module110 generates a flag due to a clogged nozzle that is shown at 310.

Referring now to FIG. 30, precise alignment of the microdeposition head50 can also be performed using the drop analysis module 110 and thefirst and/or second camera 52 and 84. More particularly, an expecteddrop location identified at 312 is compared with an actual drop locationidentified at 314. Adjustments are made to align the expected droplocation with the actual drop location. The drop alignment correctionsare performed by the drop analysis module 110.

Droplet data is acquired by one or both of the cameras 52 and 84. Thedrop analysis module 110 calculates drop volume/mass, drop velocity,angle deviation, drop quality and formation, drop and nozzleconsistency, and wetting of the nozzle plate 142. Adjustments to thenozzle firing waveforms are made based upon the collected drop data. Forexample, the nozzle firing waveform is delayed to control placement ofthe droplet. The pulse shape and width are adjusted to improve dropletquality and volume. Pulse voltage is used to adjust volume and/orquality in some situations. If other problems arise during dropanalysis, head maintenance may be performed prior to further use of themicrodeposition head 50. In addition, a user may be prompted beforeproceeding with additional microdeposition. Still other methods ofmodifying the nozzle firing waveform may be employed to impact theshape, timing, and/or volume of the droplets.

Referring now to FIGS. 31A and 31B, the microdeposition head 50 includesa plurality of nozzles 230 that are preferably spaced uniformly.However, non-uniform spacing can also be used. The angular orientationof the microdeposition head 50 is adjusted relative to a plane definedby lateral movement of the head assembly and/or the substrate. When themicrodeposition head 50 has a generally perpendicular orientationrelative to the movement of the substrate 53 (shown by arrow 336), thepitch is at a maximum value as is illustrated at 330. Likewise, an areathat is swept by the head 50 is also at a maximum value as indicated at332. As the angle of the head 50 is decreased from the perpendicularorientation, the pitch decreases as indicated at 340. Likewise, the areathat is swept by the head 50 also decreases as indicated at 342.

Referring now to FIG. 32, over-clocking generally illustrated at 350 isused to provide improved resolution and to optionally adjust for changesin the pitch of the head 50. As used herein, over-clocking refers to anincreased clock frequency relative to a droplet width and a lateral andvertical speed of the head. In microdeposition applications such as inkjets, a print grid is defined that includes grid lines that occur at aclock rate. The clock rate and lateral and vertical head speed aresynchronized to provide (or not provide) one droplet in each rectangle(or square) of the grid. In other words, the droplet to grid rectangleratio is 1:1. Some minor overlapping of droplets may occur in ink jets.Either a droplet is produced or is not produced in each rectangle orsquare of the grid.

Over-clocking according to the invention involves using a clock ratethat is substantially higher. The clock rate is increased at least 3times the conventional 1:1 ratio. In a highly preferred embodiment, theclock rate is increased 10×.

Referring now to FIGS. 31B and 32, to apply the fluid material in twoadjacent straight lines that are perpendicular to the direction ofmovement of the head 50 (e.g. arrow 336), a first nozzle 350-1 is firedat first and second times 354 and 355. A second nozzle 350-2 is fired atthird and fourth times 356 and 357, which are later than the first andsecond times 354 and 355, respectively. Likewise, a third nozzle 350-3is fired at a fifth and sixth times 358 and 359, which are later thanthe second time 356. The dwell period between the time values foradjacent nozzles is determined by the pitch of the head 50. As the pitchdecreases, the dwell period increases. Dotted lines at 360 show nozzletiming for smaller pitches.

Referring now to FIG. 33, over-clocking also allows fluid material to befired rapidly from the nozzles. A single nozzle is fired repeatedly at362 and 364 during adjacent clock cycles. For example, in FIG. 34 showsoverlapping droplets 366-1, 366-2, and 366-3 and 368-1, 368-2, and 368-3that are fired from a single nozzle. The amount of overlap and thespacing is determined by the over-clocking rate and the speed that thesubstrate 53 and/or head assembly 24 is moved.

Referring now to FIG. 35A, uncorrected nozzle waveforms 370-1, 370-2,370-3, . . . and 370-8 that correspond to droplets 374-1, 374-2, 374-3,. . . , and 374-8 are shown. The droplet 374-1 is slightly larger thandesired. Droplet 374-2 is slightly larger and earlier than desired.Droplets 374-3, 374-7 and 374-8 are okay. Droplet 374-4 is smaller andlater than desired. Droplet 374-5 is later than desired and needsimproved droplet quality.

In FIG. 35B, corrected nozzle waveforms 380-1, 380-2, 380-3, . . . and380-8 that correspond to droplets 384-1, 384-2, 384-3, . . . , and 384-8are shown. The nozzle firing waveform 381 has an adjusted amplitude. Thenozzle firing waveform 382 has an adjusted amplitude and start time. Thenozzle firing waveform 383 is left unchanged. The nozzle firing waveform384 has an adjusted amplitude and start time. The nozzle firing waveform385 has an adjusted rise slope and start time. The nozzle firingwaveform 386 has adjusted amplitude. The nozzle firing waveform 384-7and 384-8 are unchanged. As can be appreciated, the corrected nozzlewaveforms 380 have uniform or desired shape and correct timing.

Referring now to FIGS. 36 and 37, over-clocking also allows improvedresolution when defining features using microdeposition. For example,when depositing a diagonal feature line 390 without over-clocking, ajagged feature line 392 results because the droplets in the jaggedfeature line 392 must be aligned with a grid 394. When over-clocking isused in FIG. 37, the droplets 396 is placed between the grid 394 and amore accurate feature line is produced.

Referring now to FIG. 38, a first modified microdeposition head 400includes multiple microdeposition heads 402-1, 402-2, and 402-3 that areconnected together or otherwise mounted in fixed relative positions. Ascan be appreciated, the modified microdeposition head 400 provides areduced pitch as compared with a single microdeposition head 402.Referring now to FIG. 39, a second modified microdeposition head 420 isshown. The microdeposition head 420 includes multiple microdepositionheads 422-1, 422-2, and 422-3 that are moveable using actuators 424-1,424-2, and 424-3 as indicated by arrows 426-1, 426-2, and 426-3. Theangular position of the second modified microdeposition head 420 and theactuators 422 are adjusted by the controller 22 to provide a pluralityof pitches.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification and the following claims.

1. A microdeposition system that deposits droplets of fluid material ona substrate, comprising: a nozzle including a common line and a nibline; and a waveform generator that communicates with said common lineand said nib line and that generates an adjustable voltage waveform thatcauses said nozzle to fire said droplets.
 2. The microdeposition systemof claim 1 wherein said common line is connected to one of earth groundand a floating positive voltage relative to a system power ground. 3.The microdeposition system of claim 3 wherein said waveform generatordrives said nib line to a negative voltage that exceeds a firingthreshold voltage to fire said nozzle.
 4. The microdeposition system ofclaim 1 wherein said waveform generator includes an operationalamplifier (opamp).
 5. The microdeposition system of claim 4 wherein saidwaveform generator further includes a resistive ladder digital to analogconverter (DAC) that communicates with said opamp.
 6. Themicrodeposition system of claim 5 wherein said waveform generatorincludes a configuration memory with a first configuration set thatdefines a first voltage waveform.
 7. The microdeposition system of claim6 wherein said waveform generator further includes a DAC sequencer thatgenerates a voltage waveform based on said first configuration set whena firing command is received.
 8. The microdeposition system of claim 6wherein said first configuration set includes voltage and duration pairsthat define rise slope, fall slope, amplitude and timing of said voltagewaveform.
 9. A microdeposition system, comprising: a head including aplurality of nozzles; a controller that generates nozzle firing commandsthat selectively fire said nozzles to create a desired feature pattern;and configuration memory that stores voltage waveform parameters thatdefine a voltage waveform for each of said nozzles.
 10. Themicrodeposition system of claim 9 further comprising a digital to analogconverter (DAC) sequencer that communicates with said configurationmemory and said controller and that outputs a first voltage waveform fora first nozzle when a nozzle firing command for said first nozzle isreceived from said controller.
 11. The microdeposition system of claim10 further comprising a resistive ladder DAC that receives said voltagewaveforms from said DAC sequencer.
 12. The microdeposition system ofclaim 10 further comprising an operational amplifier (opamp) thatcommunicates with said resistive ladder DAC and that amplifies saidvoltage waveforms, wherein said nozzles fire droplets when said voltagewaveforms received from said opamp exceed a firing threshold of saidnozzle.
 13. The microdeposition system of claim 12 wherein said nozzlesinclude a common line and a nib line, and wherein said common line isconnected to one of earth ground and a floating positive voltagerelative to a system power ground.
 14. The microdeposition system ofclaim 13 wherein said opamp drives said nib line to a negative voltagethat exceeds said firing threshold voltage to fire said nozzle.
 15. Themicrodeposition system of claim 12 wherein said opamp is a high voltageopamp.
 16. The microdeposition system of claim 9 wherein a first voltagewaveform that is associated with a first nozzle includes at least one ofa positive pulse and a negative conditioning pulse that does not exceedsaid firing threshold.
 17. The microdeposition system of claim 16wherein said at least one of said positive conditioning pulse and saidnegative conditioning pulse precedes a firing pulse that exceeds saidfiring threshold.
 18. The microdeposition system of claim 17 whereinsaid at least one of said positive conditioning pulse and said negativeconditioning pulse follows a firing pulse that exceeds said firingthreshold.
 19. The microdeposition system of claim 9 further comprisinga configuration latch that receives a set of voltage waveform parametersfrom said controller and that loads said set of voltage waveformparameters in said configuration memory.
 20. The microdeposition systemof claim 10 further comprising a pixel latch that receives nozzle firingcommands from said controller, wherein said pixel latch communicateswith said DAC sequencer.
 21. The microdeposition system of claim 9wherein said configuration memory stores a plurality of sets of voltagewaveform parameters for each of said nozzles.
 22. The microdepositionsystem of claim 21 further comprising a configuration set selector thatselects one of said sets of voltage waveform parameters based onoperating conditions of said nozzle.
 23. A method for firing droplets offluid material in a microdeposition system, comprising: providing anozzle including a common line and a nib line; and generating anadjustable voltage waveform that causes said nozzle to fire saiddroplets.
 24. The method of claim 23 further comprising connecting saidcommon line to one of earth ground and a floating positive voltagerelative to a system power ground.
 25. The method of claim 24 furthercomprising driving said nib line to a negative voltage that exceeds afiring threshold voltage to fire said nozzle.
 26. The method of claim 25further comprising: storing a first configuration set that defines afirst voltage waveform; and generating a voltage waveform based on saidfirst configuration set when a firing command is received.
 27. Themethod of claim 26 wherein said first configuration set includes voltageand duration pairs that define rise slope, fall slope, amplitude andtiming of said voltage waveform.
 28. A method for operating amicrodeposition system, comprising: providing a head including aplurality of nozzles; generating nozzle firing commands that selectivelyfire said nozzles to create a desired feature pattern; and storingvoltage waveform parameters that define a voltage waveform for each ofsaid nozzles.
 29. The method of claim 9 further comprising generating afirst voltage waveform for a first nozzle when a nozzle firing commandfor said first nozzle is received from said controller.
 30. The methodof claim 28 wherein said nozzles include a common line and a nib line,and further comprising connecting said common line to one of earthground and a floating positive voltage relative to a system powerground.
 31. The method of claim 30 further comprising driving said nibline to a negative voltage that exceeds said firing threshold voltage tofire said nozzle.
 32. The method of claim 28 further comprisinggenerating a first voltage waveform that is associated with a firstnozzle and that includes at least one of a positive conditioning pulseand a negative conditioning pulse that does not exceed said firingthreshold.
 33. The method of claim 32 wherein said at least one of saidpositive conditioning pulse and said negative conditioning pulseprecedes a firing pulse that exceeds said firing threshold.
 34. Themethod of claim 33 wherein said at least one of said positiveconditioning pulse and said negative conditioning pulse follows a firingpulse that exceeds said firing threshold.
 35. The method of claim 28further comprising storing a plurality of sets of voltage waveformparameters for each of said nozzles.
 36. The method of claim 35 furthercomprising selecting one of said sets of voltage waveform parametersbased on operating conditions of said nozzle.